Solar powered products often include a means of configuring their energy consumption based on battery and battery charge parameters. This allows the energy consumption of the device to be matched with the amount of solar energy the device receives and stores, maximizing the performance of the device for a given location and preventing failure of the device at a critical time.
For example, a solar powered light may have an adjustable light intensity, which is generally set as a percentage of the light's maximum brightness. A second configurable parameter is the flash pattern, which is generally set as a given number of illuminations in a specified period of time. It is important that the light be able to receive and store sufficient solar energy to allow it to illuminate to the specified intensity for the specified number of flashes.
The maximum amount of energy a device can receive from the sun and store can vary greatly, depending on the geographic location of the device. For example, Los Angeles, Calif. typically receives three times the solar energy of Seattle, Wash. Accordingly, a solar powered light optimized for Los Angeles may not work for certain applications in Seattle.
It is therefore known to use power management systems to try to optimize the use of a given lighting system for the ambient conditions.
U.S. Pat. No. 6,028,597 discloses a power management system for maintaining constant brightness of the lighting elements in signage by controlling the duty cycle of a light controller. The system decides what illumination level can be maintained for a given period of time, taking into account such variables as ambient light conditions, level of charge remaining in the batteries, the availability of an alternative power supply, the length of dark time during which the lights are expected to be illuminated, any expected periods of cloud cover or solar absence, and the position of the solar array relative to the sun. The system then determines the maximum illumination level that can be maintained, having regard to all of the variables, and sets a duty cycle that is achievable by the power available to the system for the anticipated time period. However, in areas where less light than anticipated is available, or where the dark time is longer than anticipated, the system could deplete its power level and be unable to maintain the programmed level of illumination. Further, there is no assurance that the computed maximum level of illumination will meet the minimum level of illumination required by the installer, decreasing the effectiveness of the system once available power levels begin to drop.
U.S. Pat. No. 6,685,334 teaches extending the life of associated energy storage devices by selectively charging and discharging the devices, while U.S. Pat. No. 4,751,622 teaches extending the operational life of a solar powered construction light with a self-controlled on/off cycle. However, neither patent teaches any means to ensure that a minimum level of sunlight required by the installer is available at any given time. It is therefore not certain that sufficient solar power would be available to operate the devices during the life cycle of the devices.
U.S. Pub. No. 20080215186 describes a system and method for environmental control, in which environmental values such as available environmentally generated electricity are measured. A priority device interfaces with a user to define a goal that corresponds to a hierarchy of environmental objectives. The control module of the system then uses a mathematical algorithm to adjust its own components to correlate the environmental values and the user-defined goal so as to generate a set of output device settings. The control module is electrically coupled to the output device to facilitate adjustment according to the output device settings, so as to affect the environmental values in a manner consistent with the goal. However, there is no information relating to the process followed by the control module if the user has set goals that the system is incapable of reaching, given the environmental factors at the system's geographic location.
European Pub. No. EP1957878 also discloses a method for distributing the power of a power supply system to various demands, i.e. heating, hot water, and power generation. The power is distributed based on a prediction about the temporal availability of the amount of solar power by taking into account weather data and a prediction about the utilization of each of the three types of power consumption based on empirical values in such a way that the utilization ratio is maximized. Again, this method does not contemplate situations where sufficient power to meet the various demands of the installer can not be generated.
Further, it may be preferable to design a system of solar powered devices to be user-configured, to maximize the flexibility of a system and the elements within the system. This allows the installer to personalize a given system for specific applications. However, minimal guidance is often provided or accepted to assist the installer in calculating and implementing the optimal configuration. As a result, an installer may configure a device to desired parameters for his particular application, only to find that the device does not have enough energy to operate as instructed. This results in user frustration.
U.S. Pat. No. 4,481,562 discloses a self-contained signaling apparatus including a solar generator that can be directionally adjusted based on the geographical position of the apparatus, in order to maximize the amount of sunlight gathered with the photoelectric cells on the solar generator. However, because there is no means to verify that adequate sunlight will be available, the patent also teaches that the solar generator preferably includes several extra photoelectric cells, in order to ensure that sufficient solar energy may be gathered to power the apparatus. U.S. Pat. No. 4,484,104 also discloses a solar powered lighting system in which the solar cell array can be physically directed towards the anticipated position of the sun. In this case, there is no discussion of what happens if insufficient sunlight is available to charge the solar array and power the lights.
It is therefore an object of the present invention to provide a solar powered device that overcomes one or more of the foregoing deficiencies. The present invention provides a solar powered device that stores information about its local solar environment, thereby allowing the energy consumption of the device to be tailored to the particular geographical location of the device and to manage the operating parameters that will be permitted for the device.
These and other objects of the invention will be better understood by reference to the detailed description of the preferred embodiment which follows.